This invention relates to the art of plastic material pumping and dispensing apparatus, and pertains more particularly to improved pumping apparatus useful for handling hot melts, epoxy materials, adhesives and the like.
Hot melt and plastic material dispensers are known in the prior art which dispense plastic materials directly from the shipping container or barrel. Commonly, such devices include an arrangement for lowering a combined follower, heating element, and pump directly into the open end of the shipping container, for liquefying or melting the plastic material in the region directly below a heated platen, and for delivery by pump of the liquefied material to a remote location.
Commonly, such dispensing apparatus includes a follower plate or platen assembly which carries a seal about its periphery, which carries, supports or incorporates a pump, and which usually carries, supports or incorporates a heater or heated segment on the bottom thereof exposed directly to the plastic material within the container, for liquefying the plastic material, and for delivery of such plastic material to the inlet of the pump. Either a platform may be provided by means of which the container is elevated or a mechanism may be provided by means of which the plate assembly is lowered into the container.
Commonly, dispensing apparatus of the type described above is provided with either a rotary or a reciprocating pump which has an inlet positioned to receive material from a region underlying the platen for delivery to a remote position. For example, centrally positioned centrifugal type pumping apparatus in combination with hot melt dispensing apparatus is shown in Von Haase, U.S. Pat. No. 2,522,652 issued Sept. 19, 1950 and Hooker, U.S. Pat. No. 3,031,106 issued Apr. 24, 1962.
Skonberg, U.S. Pat. No. 3,282,469 issued Nov. 1, 1966 states that either reciprocating or rotary pumping apparatus may be used, but no specific pump construction is shown.
Weitzel, U.S. Pat. No. 3,113,705 issued Dec. 10, 1963, shows an airmotor driven pump of the type used for pumping lubricants, with a tubular pump body extending down through a cap plate into an axially offset receiving chamber.